This invention relates to reduction gears for light transport vehicles of the type generally powered by an electric motor or small gasoline engine. More particularly, the invention relates to construction of housings which contain spur or helical gearsets utilized in such reduction gear assemblies.
The problems inherent in maintaining "parallelism" or alignment of multiple parallel shafts are legion. In the prior art, utilization of parallel shafts in gear reduction systems has required two-piece housings, wherein each half is machined separately and then bolted together. Inherent in this practice is a slight mismatch of bearing bores due to tolerance accumulation in the separate machining processes. Additional costs are attributed to the use of two castings, machining steps, and extra assembly time required.
More desireable would be a unitary or one-piece design wherein bearing bores could be machined into a unitary housing, hence eliminating the above-mentioned bore mismatch problem. Also, use of a one-piece housing would eliminate any additional mismatch created in the bolting of the two halves together. The resultant accuracy would allow the gears on the parallel shafts to consistently run much closer to their ideal or theoretical positions, and as a result would improve the efficiency, durability and noise characteristics of the gear train operation. Such a one-piece housing would also have greater strength than the two-piece designs, in addition to utilizing fewer parts and requiring less labor in assembly.